Cardiovascular Variability Analysis under Gradually Guided Breathing Protocol

Abstract

Slow and regular breathing can make beneficial effects on cardiovascular system and autonomic nerve system. Many researches studied the cardiovascular variabilities under paced breathing rate of 0.25 Hz and 0.1 Hz, but few quantitative data are available describing the relationships between the cardiovascular variables during the slow and regular breathing procedure, and mechanism of the beneficial effects behind the slow breathing is still unclear. The aim of this study was to investigate the relationships between the cardiovascular variables with a gradually paced breathing rate from 14BPM to 7BPM. 13 of 16 volunteer's experiment data were analyzed. RR and PWTT interval, baseline changes of RR interval and PWTT, Respiratory sinus arrhythmia (RSA), and cross-correlation function between PWTT and RR were calculated. With the breathing rate from 14BPM to 7BPM gradually, RR interval changed from 170(170+ 46) ms to 261(261+93) ms, PWTT changed from 11(11 + 5) ms to 23 (23+7) ms, RSA changed from 103(103 + 37) ms to 202(202+ 97) ms, the baseline changes in RR interval ranged from 865(865 + 94) ms to 868(868 + 92) ms, the baseline changes in PWTT ranged from 160(160+16) ms to 167(167+13) ms, The mean correlation function r ranged from 0.70 to 0.78 with a maximum amplitude of r = +0.78, with the offset in RR changes leading (PWTT) changes by quarter-beat as the breathing rate below 11BPM. We conclude that cardiovascular variabilities get increased during this gradually paced breathing with breathing rate from 14BPM to 7BPM and the baseline of PWTT gets enhanced with the breathing rate getting lowed, but the baseline of RR interval changes little. Gradually paced breathing from 14BPM to 7BPM can make effect on the baseline change of PWTT, the baseline changes of PWTT can be regarded as an effective parameter to evaluate the cardiovascular reaction to slow and regular breathing practice.